Pregnancy Calculators

Pregnancy Calculators - Plan and Track Your Pregnancy

Whether you are trying to conceive or already pregnant, accurate date calculations help you plan appointments, understand your fertile window, and track gestational milestones. These calculators use standard obstetric methods (Naegele’s rule, luteal phase dating) used by obstetricians and midwives worldwide.

Thirteen Pregnancy Calculators

Breastfeeding Calorie Calculator - Calculate your daily calorie needs while nursing using the Mifflin-St Jeor equation. Enter age, weight, height, activity level, and breastfeeding status (exclusive, partial, pumping, or weaning) to get BMR, TDEE, breastfeeding calorie add-on, total daily target, and a safe weight-loss target floored at 1800 kcal/day.

Clomid Ovulation Calculator - Predict your Clomid dosing dates, ovulation window (5-10 days after last dose), fertile window, best intercourse timing, pregnancy test date, and estimated due date. Supports Day 3-7, Day 5-9, and other Clomid protocols. Enter your LMP and cycle length for instant personalised dates.

Fertility by Age Calculator - See estimated monthly conception rates, 6 and 12-month conception probabilities, miscarriage risk, and Down syndrome risk by maternal age (18–55). Two modes: Fertility by Age (full statistical profile) and Cycles Tried (how do you compare to others at your age after N months of trying). Based on ACOG guidelines and published obstetric research.

Ovulation Calculator - Find your estimated ovulation date, 6-day fertile window, next period date, and estimated due date if conception occurs. Shows 3 upcoming cycle windows in a table. Uses LMP and average cycle length with the standard luteal-phase formula.

Due Date Calculator - Calculate your estimated due date (EDD) from last menstrual period (Naegele’s rule), conception date, or ultrasound scan. Adjusts for cycle length, shows current gestational age in weeks and days, trimester, and key pregnancy milestones.

Conception Calculator - Find your estimated conception date by working backwards from your due date (EDD minus 266 days), or forward from your last menstrual period (LMP + cycle length minus 14). Shows gestational age in weeks and days, trimester, fertile window, and days remaining to the due date.

Gestational Age Calculator - Calculate exact gestational age in weeks and days from your last menstrual period (LMP) or estimated due date (EDD). Shows trimester, estimated due date, conception date, days remaining, and your next key pregnancy milestone. Supports both LMP-based and EDD-based input modes.

IVF Due Date Calculator - Calculate your IVF estimated due date from embryo transfer date (Day 3, Day 5, or Day 6 blastocyst) or egg retrieval date. Shows current gestational age in weeks and days, trimester, days remaining, and key milestones including anatomy scan, viability at week 24, and full term at week 39.

Mean Sac Diameter Calculator - Estimate gestational age from ultrasound sac measurements (length, width, and height) or a direct MSD value using the Hellman formula (MSD + 30 days). Shows LMP estimate, estimated due date, and an ACOG 2020 clinical reference for expected yolk sac and embryo visibility at each MSD size.

Pregnancy Test Calculator - Find your earliest possible test date (10 DPO) and most reliable test date (14 DPO, missed period day) from your LMP and cycle length or your ovulation date. Gives a live daily recommendation: too early, early detection window, or reliable window. Based on hCG doubling biology and standard home test detection thresholds.

Reverse Due Date Calculator - Work backwards from your estimated due date or actual birth date to find your estimated last menstrual period (LMP) and conception date. Adjusts for cycle length. Shows a 6-day conception window based on sperm and egg viability. Two modes: From Due Date and From Birth Date.

VBAC Calculator - Estimate the likelihood of successful vaginal birth after cesarean using the Flamm-Geiger scoring system. Enter maternal age, prior vaginal delivery history, cesarean indication, and cervical exam findings for a score of 0 to 10 and a corresponding estimated success rate. Two modes: Admission Score and Antenatal Estimate.

VTE Risk Score Calculator in Pregnancy - Calculate venous thromboembolism risk in pregnancy using the RCOG Green-top Guideline 37a scoring system. Outputs a total risk score and prophylaxis recommendation (LMWH duration or mobilization). Two modes: Antenatal and Postnatal. Covers prior VTE, thrombophilia, BMI, comorbidities, cesarean delivery, and 15 other validated risk factors.

Understanding Conception and Ovulation Timing

Conception occurs when a sperm successfully fertilizes an egg during ovulation. Ovulation typically happens 14 days before the next expected period, regardless of cycle length. Only the follicular phase (LMP to ovulation) varies between women; the luteal phase (ovulation to next period) is consistently 14 days. This is why cycle-length-adjusted due dates differ from the standard 28-day Naegele’s rule: the due date shifts by exactly the number of days your cycle differs from 28.

The fertile window spans 6 days: the 5 days before ovulation and ovulation day itself. Conception rates are highest (25-30% per day) on the two days immediately before ovulation and on ovulation day. Sperm viability of up to 5 days explains why sex earlier in the fertile window can still result in conception.